The How Nice is Too Nice Conundrum

Last week our neighbors (who are either from China or Taiwan) brushed our car while pulling into their parking stall. They rushed to our door, panic-stricken about the small scratch they had made. After I told them it was no big deal, it just blended in with our other dings, they still seemed very concerned, but finally let it go. I thought nothing of it, but last night they showed up at our door with a box of Cheesecake Factory cheesecake and a bottle of wine. I can't figure out if they think I'm just really nice or if they think I like to hold onto grudges and that scratch is going to come back to haunt them. I had to explain to them that I couldn't accept the wine since drinking alcohol is against my religion and I'm afraid they went home kicking themselves for offending me. Part of me wonders if they would feel better if I just fixed the scratch and let them pay for it, but I would hate to make them pay excessive amounts to fix a small, cosmetic scratch on a car we don't plan on re-selling. I'm now afraid to do anything nice for them in case they just feel like they'll always be in our debt, which is too bad, because they seem like a really nice family.